Standard methods of signalling had become established in the English, Dutch and French navies well before the end of the seventeenth century, and apart from developments in codes and techniques, they remained unchanged un-til after 1815. In port, in daytime, signals were made with guns and by moving sails. At sea flag signals were best for communicating with the fleet, guns being used to draw attention to the signal, but only in the eighteenth century was the system of employing frigates to relay signals developed. In the seventeenth century it was usually necessary in battle for orders to be sent through the fleet by boat. At night signals were made by fastening lanterns in the rigging, burning false fires, and firing sky rockets. Fog signaling was very limited in scope, and was made with guns, bells and muskets firing in distinct patterns, and always in the same direction.

In 1738, a Frenchman, de la Bourdonnais, devised the first numerical flag code, the basis on which all later development of flag hoist signalling was based. De la Bourdonnais assigned a different flag to each number, 0 through 9. With three sets of flags, a ship could make 1,000 different combinations of three-flag signals. Coupled with a dictionary assigning a meaning to each combination, de la Bourdonnais's system would have permitted a marked advance in the sophistication of naval communications. Unfortunately, his idea was never adopted by the French Navy, but it was followed up a quarter century later by another Frenchman, Sebastian Francisco de Bigot, founder of the French Marine Academy at Brest, who published Tactique Navale ou Traite des Evolutions et des Signaux in 1763. In addition to the ten numerary flags, Bigot prescribed predefined meanings for 336 different hoists and added both a preparatory flag to signal that a coded message would be transmitted and a requirement that the receiving ship acknowledge the signal.

Signals development in the Royal Navy lagged behind that of the French but After the Seven Years War, which ended in 1762, the British Navy developed, under Lord Howe's leadership, a numerical system employing two flags and a weft (a partially furled flag) which greatly increased the possible number of signals, and increased the speed of transmission. As early as 1776 when Howe commanded on the North American station he conceived the idea of separating signals and tactics, which greatly improved the speed of transmission and the accuracy with which signals could be read. In 1782 he applied his new system to the Channel Fleet, and in 1790 he gave the Royal Navy a true numerical system of signalling. Howe's innovations included the use of substitute or repeater pennants, so that only one set of flags was necessary instead of three, and the introduction of additional control flags. Howe also introduced the concept of assigning a number to each ship so that signals could be addressed individually instead of collectively. Lord Howe's numerary system was revised and expanded over the last decade of the 18th century, culminating in the Admiralty's 1799 Signal Book for Ships of War, which promulgated the individual flag designs used by the Royal Navy throughout the Napoleonic Wars and the War of 1812, although the number assigned to each flag changed periodically or whenever a signal book was compromised.

In 1800, Rear Admiral Sir Home Popham expanded on the Howe system with his Telegraphic Signals or Marine Vocabulary. Working from the ten existing numeral flags of the Admiralty Signal Book, Popham developed the world's first alphabetic flag signal system. Flags one through nine were assigned to letters A through J (I and J counting as a single letter). Two flag hoists accounted for the rest of the alphabet. Popham's code included a numbered dictionary of 3,000 predefined words and phrases, plus the capability to spell out words not included in the dictionary. A signal in Popham code was identified by an initial hoist of red and white flag divided diagonally. To maximise utility while minimising the signal complexity, Popham used a multiple definition process for any given word or phrase code, thus:-

Code   Meaning
 66   appear/appeared/appearing/appearance
   :      :
 69   approve/approved/approving/approval
it was up to the receiver of the signal to select the particular interpretation within the context of the overall signal. The Admiralty adopted the Popham system to augment that of the 1799 Admiralty Signal Book.

     A page from the Admiralty Day Signal Book for Ships of War, 1799









The flags are intended to represent the figures placed opposite to them in the annexed table. A flag hoisted alone, or under an-other flag, is to represent units; when two flags are hoisted, the upper flag is to represent tens; when three are hoisted, the uppermost is to represent hundreds, the next tens, and the lowest units.


When the substitute flag is hoisted under other flags, it is to represent the same figure as the flag immediately above it: when the substitute pendant is hoisted under, two flags, it is to represent the same figure as the upper flag of the two. For example, to represent the N° 33, the substitute flag will be hoisted under the flag representing 3, and to represent the N° 303 the cypher flag will be hoisted under the flag representing 3, and the substitute pendant under both.


In blowing weather, or when much sail is set, as it may he inconvenient to hoist three flags at the same place, the two upper flags may be hoisted at one part of the ship, and the lowest flag, or the substitute pendant, at any other part.


If the Admiral should have reason to believe that the enemy has got possession of these signals, he will make the signal for changing the figures of the flags, and when that has been answered by every ship, he will hoist the numeral flags, two or three at a time, the uppermost flag of those first hoisted is to represent 1; the next below it, 2; and so on till all the flags have bath hoisted, the tenth flag representing the cypher, and the last being the substitute flag. To prevent mistakes, every ship is to hoist the same flags as the Admiral, and in the same order; the flag officers are to be particularly attentive to see this done,, and to shew the distinguishing signal of any ship in which they observe a mistake. The figure which, by the new arrangement, each flag is to represent, is to be immediately entered in every ship’s signal-book.


The flags are always to represent the figures placed opposite to then in the annexed table, in signals made in port, or to the signal posts on shore; or by ships meeting accidentally at sea. But an Admiral may make any other arrangement for the use of the fleet he commands while at sea.























† Affirmative answer from private ships


There are two main sources for Nelson's famous Trafalgar signal "ENGLAND EXPECTS EVERY MAN WILL DO HIS DUTY", this variant was recorded by Captain Blackwood of the Euryalus frigate which was acting as a signal repeating ship between the Weather and Lee Columns of the fleet. John Pascoe, acting signals lieutenant of the Victory, however recorded this signal intended to "amuse the fleet" as "ENGLAND EXPECTS THAT EVERY MAN WILL DO HIS DUTY". All agree however that it was Nelsons original intent to signal "ENGLAND CONFIDES…" but all contemporary sources agree that the signal Lieutenant suggested "EXPECTS" instead of "CONFIDES" because it was in the Popham code and therefore did not need to be laboriously spelled out. If the concern was the length of the signal, it seems strange that a basically redundant word like "THAT" would be included. The Euryalus recorded the signal took four minutes to execute and this should be seen in the context of Pascoe having been instructed to make all haste as Nelson wished to hoist the signal for 'close action' immediately afterwards.

The second source of confusion is in the actual  signal flag values on the day, contemporary sources suggest that flags corresponding to values of the 2, 5 and Substitute flags given in the Admiralty Daybook had been altered for the day of the battle: This is wholly in line with normal practice where "If the Admiral should have reason to believe that the enemy has got possession of these signals" he will set about "changing the figures of the flags" at the earliest opportunity.

Whatever the exact wording of the signal, and contrary to common belief, it would appear that for the majority of ships in Nelson's fleet, the signal passed without remark. Many ships logs carry no mention of the signal but almost all of them recorded the standard signal Number 16 for 'Close Action', which immediately followed it. This suggests that either Popham's code book had not reached every ship in the fleet or that Victory and her repeaters were simply out of sight.

Even for those ships that did receive the message, the content was often garbled by the time it reached the men: in the Minotaur it was recorded as, "the Victory made a general telegraph the purport of which was I hope every man will do his duty like an Englishman". In the Polyphemus, Henry Blackburn interpreted the message as, "Hope Every English man would behave with his usual heroism and exert every means to destroy the Enemies of their Country". Only a few ships both received the signal, and passed its message on to the men, significantly, these were ththe ships commanded by captains who had served with Nelson before. In Dreadnought, for example, George Hewson recalled that on "the purport of this [signal] being explained to the ships company, it was received with a burst of applause and every individual seemed animated with a determination to conquer".

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By 1813 an expansion and revision of the Popham code contained 6,000 set phrases and some 60,000 words.

The French also continued to develop their tactical systems. In 1763 Admiral the Vicomte de Morogue produced in Tactique Navale, a work which sought to reduce tactics to formulae, and in 1776 Captain du Pavillon introduced a signaling system using grid tablature to allow two-flag hoists, flown where most easily seen, to convey hundreds of messages. The American War of Independence was the highest competitive point in French and British tactics. Beginning with the Vicomte de Grenier in 1777, the demand in the French navy for offensive tactics increased. As late as 1806, however, the French Navy rejected the proposed adoption of a numerical system of signaling, by a vote taken at each of the naval bases, and voted instead to continue using du Pavilion's tabular system, which they retained until after the end of the Napoleonic Wars.

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In addition to the basic communication described above, there was a need to identify the ship to which the signal was addressed. An admiral or commodore would draw up a table of one and two flag hoists, by flag position and elevation on the ship at which they would be shown, to identify the ship to which the following signal would be addressed. For example:-

     Flag Table of English Ships at Camperdown, October 1797

Flag Table of English Ships at Camperdown, October 1797.

Private Signals

Two ships meeting at sea had to be able to identify each other, both to establish seniority and more importantly, to ensure the ship was friendly. With so many captured ships in service, it was impossible to tell by form or fitting if a ship was a part of your own navy, further, it was not uncommon for a ship to fly the flag of neutral or allied power as a ruse de guerre.

This was accomplished by 'private signals' which comprised a sequence of challenge and response drawn from a table of flag codes and hoist positions that changed every ten days. The captain was required to ensure that these signal tables were sunk in event or threat of capture. At night, a system of coloured lights, shown at different heights in the rigging, was used in place of flags and would conclude with a close pass between ships when a code words were exchanged.

In bad weather (Fog etc.) a somewhat clumsy system of gun and musket shots, horn, bell and drum rolls and even fire crackers were used.